Diastereoselective Formation of Ruthenium-Isocyanide and -Acetylide Complexes with Planar-Chiral Cyclopentadienyl-Phosphine Ligands

The reaction of ruthenium complexes [(η⁵:η¹-2-Me-4-R-C₅H₂CO₂CH₂CH₂PPh₂)Ru(PR‘₃)(NCMe)][PF₆] (R = Me, Ph, Bu^t; R‘ = Ph, Me, OPh) possessing planar-chiral cyclopentadienyl-phosphine ligands with tert-butyl isocyanide resulted in the diastereoselective formation of ruthenium-isocyanide complexes (up to >99% de) under kinetic control. The reaction with phenylacetylene followed by treatment with alumina gave acetylide complexes diastereoselectively (up to >99% de). The configuration of the products was determined by X-ray analyses as well as NOE measurements. In both reactions, the stereochemistry of the ruthenium atom in the substrate did not influence the diastereoselectivity of the products, although the substituent on the cyclopentadienyl ring and the phosphorus ligands on the ruthenium atom showed steric effects on the selectivity.